its not aluminum, Al element. its a compound of something, some kind of new technology, aluminum alloy that is. its so strong its use for space crafts. =)

 

appearently not strong enough if it can't handle the heat of the 3rd cylinder and the turbo..

 

true about the #3 cylinder. that's why, if you want to modify the WRX or the STi, then you would have to move the turbo a bit higher in the engine bay. i've seen this on mostly all the modified WRX's and STi's such as JUN's 500hp WRX. they've relocated the turbo. as well as some other things such as the alternator.

 

appearantly not strong enough for an iron block either, they over heat more often if you mod it up inefficiently just as if you mod a wrx inefficiently.

 

I am new to Subarus so excuse me if I am asking dumb questions. I've spent the better part of the last few years on the other side Hondas and sweet German machinary.

Are the STI sleeves iron or not?
Closed deck or open?
What is the compression ratio?
Rods and pistons forged?
What is the stroke to rod ratio?
Any know issues with the crank on the EJ20 or EJ25? I know the 4G63 had (has?) some issues with crank walking, but haven't heard anything about the Subaru cranks (has anyone broken one?)?

I have a lot of questions about the head too, but I'll save that for another post

 

Iron sleeves yes
Exhaust valves are sodium filled for better heat dissipitation,
Just like the V-dubs, BMWand vetts.

Closed deck yes
8:1 or 8.5:1 can someone confirm?
Rods forged
Pistons are cast on WRX but could be forged on STI(?)
Stroke to rod ratio unknown
There are no known crank issues.
Yes I know a bunch of people that have broken their subarus.
Yes you will fry a clutch.
Yes you can Granade a transmission or 2.
Yes you can skip a tooth on the cam gear and bend some valves.
No there have not been any broken cranks.






The main Problem with the crank walk on mitsubishi is the ultra heavy pressure plate people like to install.
There is only ONE main bearing in there 4g63.
The real problem might be mismatched parts for the application.
Drag clutch for daily driving?
Instead of going to a heavy pressure plate why not a multi plate clutch?
Smaller lighter and grips just as much without the hassel.

Questions people forget or never ask.

What kind of HP are you shooting for?
Will the car be used for daily driving?
Will it be used for SCCA racing?
Will it be for drag racing?
You will want to build a car for what your doing.


I WANT A.....
A 750hp daily driver/SCCA race/Rally/drag car running on 92 pump gas and dummping 20psi of boost all day
on a RB52 IHI turbo.
and still get 31 mpg on the Hwy.
Not gonna happen.

There are a lot of resources here on the boards and the people are friendly, they like to roast new guys sometimes so hang tight
and have fun.
Besides people have clubs to keep other people out.
Thats why clubs were invented.
Welcome to the boards!

 

Thanks! Any idea what the size of the fuel injectors are? What options are available for ecu replacement? I think Link makes one, but not sure if one is available for the US sti or not.

350-400whp should be doable, right? :-)

 

easily doable, just remove those cats and get 3 inch piping. and some grounding wires, short ram intake, boost controller.

 

I wish you were right, but I suspect that it would take a little more work. Even if the internals can handle the extra power without modification, you would still have to at least tinker with fuel delivery to make sure it can keep up with 50-75% more power without going 100% duty cycle and leaning out at the top. Then there is the issue with pulling timing while on boost and getting the ECU to respect the fact that you are going past 14.5 psi.

And even if you can make the power, what about the rest of the system? Is the clutch going to hold it? What about the tranny? axles?

And what about the turbo? Remember, we are talking about 350-400 WHEEL hp. I think I read somewhere that it is a IHI turbo? Anyone got a compressor map? If we have to run 25psi to get to the hp goals, we may be out of the efficiency curve of the turbo.

My point is that if you are right, I'd be extremely happy!

 

550cc/min last I know.

 

The internals are reinforced, they have added an extra webbing in the crank area of the block.
Closed deck
The tranny is JDM it should hold up, if you bust this tranny your a doob and doing something wrong.
Cyro treated gears.

Example situation
Lets shoot for maximum HP for a motor like this.
(This is a fuel requirment problem)
but max hp without going over 65% duty on injectors
I don't know what the max hp would be because no one has tried
to build it.

What you have
2.5 liters(2500cc)STI
Turbo unknown
.

You will have to go to 1.5x the displacement(cc) of one cyl.

i.e. 2500cc for this 2.5liter devide by 4= 625cc per cyl.

take that number and multiply by 1.5=937.5cc

Thats a 937 cc/min injector(not gonna happen) to maintain about 65% duty cycle.

Solution: Staged injection set up
Stand alone$$$
upgradded fuel lines and cooling systems
then you open your self to a can of worms unless you gots deep bank account.

300hp to the wheels very doable
You are already at 250@6k revs per Road&Track magazine.
Open the intake and up the boost.
Remove the cat redo the dump pipe, larger intercooler.
Upgrade the turbo
Fuel injectors
fuel pump
chip mod or remap or piggyback or you get it...
Go 3" exhaust only if you want top end gain. 3-4hp gain for $600 is not worth it.
But who knows certain motors run better with 3" and certain motors run better with 2.5".


400hp to the wheels then you gots problems
intake
Head work?
FMIC?
fuel pump driver?
fuel pump?
injectors?
addtional fuel lines?
Stand alone, unless you run an AIC set up, tuning the ***** is a pain.
dual injector set up?
Bigger exhaust ?
Larger turbo?
Who knows what you need.
Could be all that or maybe minor stuff.

Most transmissions like this can and will handle a 100% increase in hp its just how you treat.
Half shafts then your in for a treat they make em for about $1500
each in the UK.

At this point you can beat 90% of the cars on the street with a stock STI.
Shoot for 300-320 at the wheels and be happy that you can own one.

Hell I get nervous when I drive the dammed thing(STI) and I fly aeroplanes.
You are a Brave Man
Sorry for the loooong post dammed espresso

 

80% duty cycle should be acceptable, and running them at a higher pressure, you should be able to get by with 720cc injectors. Not sure if they will idle

Got my STI today, already put 400 miles on it. Power is good, cant wait to open it up and see what it will do.

Like most people, I will probably do the normal bolt-ons and wait for someone to figure it all out, unless there is already an affordable standalone, in which case, it shouldn't be too difficult.

PS: More ppl die driving then flying

 

is the stand alone fuel management always the way to go for an upgrade?? cause i dont really now what it means or does..

 

Heck no!
Its not the ONLY way to go.
There are ways but you gotta know what you want.

Figure what you want, how much you want to VOID the warranty and how much you want to spend.
Then build it.
Just don't complain to Subaru when you break things.

No car compay will back anything that has been modified with aftermarket parts, abused and/or has been used in a competitive event.
Read page 13 of the warranty exclussions.

If you want to play with the big boys be sure you gots the cash to repair things the factory won't cover.

If you don't have cash I suggest you buy yourself a cheaper car to
race and mod.


I'll shut up now.

 

I'll add to what El Jeffe said. If you are doing bolt-ons, the stock ECU will probably figure it out and add enough fuel to maintain the factory AF ratio, pull timing while on boost, etc. However, if your hp goals are high, and if you plan on doing things like replace your turbo, run more boost, bigger injectors, then you'll have to start thinking about replacing the stock ECU.

Replacing the ECU requires you to take your car to a shop to have it tuned; you dont just buy an aftermarket ECU and plug it in.

Is it the only way to go? That will depend on your modifications.